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Jitendra Vishwakarma, Keerti Gupta, Juhi Mishra, Asmita Garg, Rafat Malik, Amit Kashyap, Manoj Shukla, Dhirendra Singh, and Sanghamitra Bandyopadhyay

Thyroid hormones (TH) are vital for brain functions, while TH deficiency, i.e. hypothyroidism, induces neurological impairment in children and adults. Cerebellar neuronal apoptosis and motor deficits are crucial events in hypothyroidism; however, the underlying mechanism is less-known. Using a methimazole-treated hypothyroidism rat model, we investigated cerebellar autophagy, growth factor, and apoptotic mechanisms that participate in motor functions. We first identified that methimazole up-regulated cerebellar autophagy, marked by enhanced LC3B-II, Beclin-1, ATG7, ATG5-12, p-AMPKα/AMPKα, and p62 degradation as well as reduced p-AKT/AKT, p-mTOR/mTOR, and p-ULK1/ULK1 in developing and young adult rats. We probed upstream effectors of this abnormal autophagy and detected a methimazole-induced reduction in cerebellar phospho-epidermal growth factor receptor (p-EGFR)/EGFR and heparin-binding EGF-like growth factor (HB-EGF). Here, while a thyroxine-induced TH replenishment alleviated autophagy process and restored HB-EGF/EGFR, HB-EGF treatment regulated AKT-mTOR and autophagy signaling in the cerebellum. Moreover, neurons of the rat cerebellum demonstrated this reduced HB-EGF-dependent increased autophagy in hypothyroidism. We further checked whether the above events were related to cerebellar neuronal apoptosis and motor functions. We detected that comparable to thyroxine, treatment with HB-EGF or autophagy inhibitor, 3-MA, reduced methimazole-induced decrease in Nissl staining and increase in c-Caspase-3 and TUNEL-+ve apoptotic count of cerebellar neurons. Additionally, 3-MA, HB-EGF, and thyroxine attenuated the methimazole-induced diminution in riding time on rota-rod and grip strength for the motor performance of rats. Overall, our study enlightens HB-EGF/EGFR-dependent autophagy mechanism as a key to cerebellar neuronal loss and functional impairments in developmental hypothyroidism, which may be inhibited by HB-EGF and 3-MA treatments, like thyroxine.

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Mari van de Vyver

Inflammation is part of the body’s innate immune response and is an essential process that not only defends against harmful bacteria and pathogens but also plays a key role in the maintenance and repair of tissues. Under pathological conditions, there is bilateral crosstalk between immune regulation and aberrant metabolism resulting in persistent inflammation in the absence of infection. This phenomenon is referred to as sterile metabolic inflammation (metainflammation) and occurs if the initiating stimulus is not removed or if the resolution process is disrupted. Disruption of this tightly regulated immune response and its failure to resolve as is evident in metabolic disorders is not only associated with disease progression but also leads to immune senescence and should not be neglected in the clinical management of patients. This review gives an overview of the mechanisms underlying chronic metabolic inflammation, the aberrant metabolic activation of innate immune cells (neutrophils, macrophages, mast cells, dendritic cells), and its role in disease progression using obesity–diabetes as a prime example. Addressing the underlying subclinical metabolic inflammation in addition to achieving glucose control may contribute significantly towards therapeutic interventions aimed at preventing the onset of co-morbidities in diabetic patients.

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Sara Ines Peña, Matias Alfonso Rubio, Constanza del Rosario Vargas, Constanza Francisca Alanis, and Alfonso Humberto Paredes

Leukaemia inhibitory factor (LIF) is a cytokine belonging to the IL-6 family that is important at the reproductive level in the uterine implantation process. However, there is very little evidence regarding its effect at the ovarian level. The aim of this work was to study the local involvement of the LIF/LIFRβ system in follicular development and steroidogenesis in rat ovaries. To carry out this research, LIF/LIFR/GP130 transcript and protein levels were measured in fertile and sub-fertile rat ovaries, and in vitro experiments were performed to assess STAT3 activation. Then, in in vivo experiments, LIF was administered chronically and locally for 28 days to the ovaries of rats by means of an osmotic minipump to enable us to evaluate the effect on folliculogenesis and steroidogenesis. It was determined by q-PCR and WB that LIF and its receptors are present in fertile and sub-fertile ovaries, and that LIF varies during the oestrous cycle, being higher during the oestrus and meta/dioestrus stages. In addition to this, it was found that LIF can activate STAT3 pathways and cause pSTAT3 formation. It was also observed that LIF decreases the number and size of preantral and antral follicles without altering the number of atretic antral follicles, and can increase the number of corpora lutea, with a notable increase in the levels of progesterone. It is therefore possible to infer that LIF exerts an important effect in vivo on folliculogenesis, ovulation and steroidogenesis, specifically the synthesis of progesterone.

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Yang Chen, Xin Li, Jing Zhang, Mingjiao Zhang, Salah Adlat, Xiaodan Lu, Dan Li, Honghong Jin, Chenhao Wang, Zin Mar Oo, Farooq Hayel, Quangang Chen, Xufeng Han, Renjin Chen, Xuechao Feng, Luqing Zhang, and Yaowu Zheng

Obesity is caused by imbalanced energy intake and expenditure. The excessive energy intake and storage in adipose tissues is associated with many diseases. Several studies have demonstrated that VEGFB deficiency induces obese phenotypes. However, roles of VEGFB isoforms VEGFB167 and VEGFB186 in adipose tissue development and function are still not clear. In this study, genetic mouse models of adipose-specific VEGFB167 and VEGFB186 overexpression (aP2-Vegfb167tg/+ and aP2-Vegfb186tg/+) were generated and their biologic roles were investigated. On regular chow, adipose-specific VEGFB186 is negatively associated with white adipose tissues (WAT) and positively regulates brown adipose tissues (BAT). VEGFB186 up-regulates energy metabolism and metabolism-associated genes. In contrast, VEGFB167 has nominal roles in adipose development and function. On high fat diet, VEGFB186 expression can reverse the phenotypes of VEGFB deletion. VEGFB186 overexpression up-regulates BAT-associated genes and down-regulates WAT-associated genes. VEGFB186 and VEGFB167 have very distinct roles in regulation of adipose development and energy metabolism. As a key regulator of adipose tissue development and energy metabolism, VEGFB186 may be a target for obesity prevention and treatment.

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Samuel M Lee, Jose Muratalla, Marta Sierra-Cruz, and Jose Cordoba-Chacon

Peroxisome proliferator-activated receptor γ (PPARγ) belongs to a family of nuclear receptors that could serve as lipid sensors. PPARγ is the target of a group of insulin sensitizers called thiazolidinediones (TZDs) which regulate the expression of genes involved in glucose and lipid metabolism as well as adipokines that regulate metabolic function in other tissues. Non-alcoholic fatty liver disease (NAFLD) has a high prevalence worldwide and is even higher in patients with obesity and insulin resistance. TZD-mediated activation of PPARγ could serve as a good treatment for NAFLD because TZDs have shown anti-fibrogenic and anti-inflammatory effectsin vitro and increase insulin sensitivity in peripheral tissues which improves liver pathology. However, mechanistic studies in mouse models suggest that the activation of PPARγ in hepatocytes might reduce or limit the therapeutic potential of TZD against NAFLD. In this review, we briefly describe the short history of PPAR isoforms, the relevance of their expression in different tissues, as well as the pathogenesis and potential therapeutics for NAFLD. We also discuss some evidence derived from mouse models that could be useful for endocrinologists to assess tissue-specific roles of PPARs, complement reverse endocrinology approaches, and understand the direct role that PPARγ has in hepatocytes and non-parenchymal cells.

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Banrida Wahlang

Based on biological sex, the consequential health outcomes from exposures to environmental chemicals or toxicants can differ in disease pathophysiology, progression, and severity. Due to basal differences in cellular and molecular processes resulting from sexual dimorphism of organs including the liver, and additional factors influencing ‘gene-environment’ interactions, males and females can exhibit different responses to toxicant exposures. Associations between environmental/occupational chemical exposures and fatty liver disease (FLD) have been well-acknowledged in human epidemiologic studies, and their causal relationships demonstrated in experimental models. However, studies related to sex differences in liver toxicology are still limited to draw any inferences on sex-dependent chemical toxicity. The purpose of this review is to highlight the present state of knowledge on the existence of sex differences in toxicant-associated FLD (TAFLD), discuss potential underlying mechanisms driving these differences, implications of said differences on disease susceptibility, and emerging concepts. Chemicals of interest include various categories of pollutants that have been investigated in TAFLD, namely, persistent organic pollutants, volatile organic compounds, and metals. Insight on research areas requiring further development is also discussed, with the objective of narrowing the knowledge gap on sex differences in environmental liver diseases. Major conclusions from this review exercise are that biological sex influences TAFLD risks, in part due to i) toxicant disruption of growth hormone and estrogen receptor signaling, ii) basal sex differences in energy mobilization and storage, and iii) differences in chemical metabolism and subsequent body burden. Finally, further sex-dependent toxicological assessments are warranted for development of sex-specific intervention strategies.

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Adam Hagg, Eliza O'Shea, Craig A. Harrison, and Kelly Louise Walton

Although originally characterised as proteins involved in the control of reproductive function, activins, and to a lesser degree inhibins, are also important regulators of homeostasis in extragonadal tissues. Accordingly, disrupted inhibin/activin expression can have detrimental effects not only for fertility and fecundity, but also for the regulation of muscle, fat and bone mass. Indeed, only recently, two complementary mouse models of inhibin designed to lack bioactivity/responsiveness, revealed that inhibin A/B deficiency during pregnancy, restricts embryo and foetal survival. Conversely, hyper elevated levels of activin A/B, as are frequently observed in patients with advanced cancers, can not only promote gonadal tumour growth but also cancer-cachexia. As such, it is not surprising that inhibin/activin genetic variations or altered circulating levels have been linked to reproductive disorders and cancer. Whilst some of the detrimental health effects associated with disrupted inhibin/activin levels can be attributed to accompanied changes in circulating follicle stimulating hormone (FSH) levels, there is now abundant evidence that activins, in particular, have fundamental FSH-independent tissue homeostatic roles. Increased understanding of inhibin/activin activity, garnered over several decades, has enabled the development of targeted therapies with applications for both reproductive and extra-gonadal tissues. Inhibin- or activin-targeted technologies have been shown not just to enhance fertility and fecundity, but also to reduce disease severity in models of cancer cachexia. Excitingly, these technologies are likely to benefit human medicine and be highly valuable to animal breeding and veterinary programs.

Free access

Jasleen Kaur and Elizabeth R Seaquist

Glucagon is secreted by the pancreatic alpha cell and has long been known to oppose insulin action. A lyophilized form of the hormone has been available to treat episodes of insulin-induced hypoglycemia in insulin-treated people with diabetes for decades, but the difficulty of use was a barrier to widespread utilization. Newer formulations of glucagon are stable at room temperature in single-use devices that many caregivers find are easier to use than the original glucagon emergency kit. In this review , we will review what is known about the role of glucagon in normal physiology and diabetes and then discuss how the research in this area has been translated into treatment for metabolic conditions.

Open access

J N Zamarbide Losada, E Sulpice, S Combe, G S Almeida, D A Leach, J Choo, L Protopapa, M P Hamilton, S McGuire, X Gidrol, C L Bevan, and C E Fletcher

Breast cancer (BC) is the most diagnosed cancer in women worldwide. In estrogen receptor (ER)-positive disease, anti-estrogens and aromatase inhibitors (AI) improve patient survival; however, many patients develop resistance. Dysregulation of apoptosis is a common resistance mechanism; thus, agents that can reinstate the activity of apoptotic pathways represent promising therapeutics for advanced drug-resistant disease. Emerging targets in this scenario include microRNAs (miRs). To identify miRs modulating apoptosis in drug-responsive and -resistant BC, a high-throughput miR inhibitor screen was performed, followed by high-content screening microscopy for apoptotic markers. Validation demonstrated that miR-361-3p inhibitor significantly increases early apoptosis and reduces proliferation of drug-responsive (MCF7), plus AI-/antiestrogen-resistant derivatives (LTED, TamR, FulvR), and ER- cells (MDA-MB-231). Importantly, proliferation-inhibitory effects were observed in vivo in a xenograft model, indicating the potential clinical application of miR-361-3p inhibition. RNA-seq of tumour xenografts identified FANCA as a direct miR-361-3p target, and validation suggested miR-361-3p inhibitor effects might be mediated in part through FANCA modulation. Moreover, miR-361-3p inhibition resulted in p53-mediated G1 cell cycle arrest through activation of p21 and reduced BC invasion. Analysis of publicly available datasets showed miR-361-3p expression is significantly higher in primary breast tumours vspaired normal tissue and is associated with decreased overall survival. In addition, miR-361-3p inhibitor treatment of BC patient explants decreased levels of miR-361-3p and proliferation marker, Ki67. Finally, miR-361-3p inhibitor showed synergistic effects on BC growth when combined with PARP inhibitor, Olaparib. Together, these studies identify miR-361-3p inhibitor as a potential new treatment for drug-responsive and -resistant advanced BC.

Open access

Shiho Fujisaka, Yoshiyuki Watanabe, and Kazuyuki Tobe

The human body is inhabited by numerous bacteria, fungi, and viruses, and each part has a unique microbial community structure. The gastrointestinal tract harbors approximately 100 trillion strains comprising more than 1000 bacterial species that maintain symbiotic relationships with the host. The gut microbiota consists mainly of the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. Of these, Firmicutes and Bacteroidetes constitute 70–90% of the total abundance. Gut microbiota utilize nutrients ingested by the host, interact with other bacterial species, and help maintain healthy homeostasis in the host. In recent years, it has become increasingly clear that a breakdown of the microbial structure and its functions, known as dysbiosis, is associated with the development of allergies, autoimmune diseases, cancers, and arteriosclerosis, among others. Metabolic diseases, such as obesity and diabetes, also have a causal relationship with dysbiosis. The present review provides a brief overview of the general roles of the gut microbiota and their relationship with metabolic disorders.